Doolittle suffered a right calf strain earlier this week, while Cook is nursing an inflamed right shoulder that could prevent him from throwing for a couple of weeks.

But when asked if there's any concern the right-handed Cook could still be sidelined come Opening Day, manager Bob Melvin said, "At this point, none."

"We've shut him down here recently," Melvin explained Friday, when A's pitchers and catchers reported. "He'll probably be a couple weeks behind guys, but we don't think it's a serious thing. We just want to make sure that he's healthy come Opening Day. He'll be a little bit behind everyone as far as when he gets on the mound again, but he's thrown some bullpens to this point.

"We're just trying to be proactive with this. He feels good now, and everything he's been doing here the last few days, as far as exercises, he's done very well."

Doolittle, meanwhile, injured his calf while running a couple of days ago. The southpaw is likely to be held back from throwing on Saturday, when batterymates gather for their first official workout, but Melvin assured "he shouldn't be long after that."

Like Cook, Doolittle threw six or seven bullpen sessions leading into camp, so playing catch-up shouldn't be much of an issue.

The setup men combined for 136 1/3 innings in their second big league seasons last year, but just 53 2/3 of them were recorded after the All-Star break, as management kept a close eye on their workloads.

"Last year, based on the year before," Melvin said, "we really backed off some of our relievers with the workload, especially the younger guys. That will always be important to us."

The addition of Luke Gregerson, as well as the rapid rise of Dan Otero, will allow the A's to rotate pitchers more freely in the later innings this year, rather than rely solely on Cook and Doolittle to set up the ninth.

Cook compiled a 2.54 ERA and 1.29 WHIP in 71 games in 2013 (67 1/3 innings). Doolittle appeared in 70 (69 innings), sporting a 3.13 ERA with a 0.96 WHIP while averaging 7.8 strikeouts to 1.7 walks per nine innings. Together, they totaled 11 wins and four saves.

Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.